In addition to regular dental checkups and periodic professional cleaning of the teeth to remove plaque, a regular personal regimen of dental hygiene is essential to maintaining the health and appearance of the teeth and gums. The use of a manual toothbrush having an array of bristles mounted near one end of some form of handle is the most familiar and commonly-used implement for this purpose. Also known are various forms of mechanized brushing devices in which energy in various forms are imparted to the bristles in various other ways including electromechanical drives which cause tufts of bristles to rotate either unidirectionally or biodirectionally in an oscillatory fashion. Toothbrushes in which ultrasonic energy is imparted to bristles are also known in the art. The foregoing types of toothbrushes can usually be selected from a range of bristle stiffness ranging from relatively stiff or "hard" to relatively compliant or "soft".
Toothbrushes of the types described above are effective for cleaning most areas of the teeth, dental prosthesis, and orthodontic appliances but have significant limitations. These limitations stem mainly for the need of these devices for some form of a relatively long and rigid or semi-rigid handle and the fact that bristles, by their nature, clean most effectively when they extend substantially perpendicularly to the surface being cleaned. Given the positioning and movement constraints imposed by using devices having such handles within the confines of a human mouth, it is simply not possible to position the brush and move its bristles so that maximally effective cleaning can be realized over all areas of the teeth, dental work and gums. These disadvantages have been ameliorated somewhat by various improvements directed toward improving the maneuverability of toothbrush heads such as making the heads smaller, angling the brush handle, providing a flexible joint in the handle and arranging bristles of varying lengths to form tufts having special contours intended to improve their penetration of irregularly shaped structures. These solutions however, are not entirely sufficient to effectively clean all areas especially those adjacent spaces or gaps such as those present between teeth, especially when root surfaces are exposed.
An alternative to brushing which is claimed to be effective for cleaning teeth both above and below the gum line as well as for dislodging foreign matter from between teeth involves the use of devices which operate by projecting a stream of water or other fluid either continuously or in a rapidly pulsating manner. Like many of the mechanically-powered toothbrushes, these devices tend to be relatively expensive and require a power source. They also require a fluid supply and cannot be used effectively with toothpaste. Since these devices tend to be most effective when the fluid stream is directed normally to the surface to be cleaned, their effectiveness for cleaning between teeth is limited.
It has been both well known and widely recommended to use a flexible filament such as dental floss or dental tape to remove food or other foreign matter from the gaps between teeth both above and below the gumline. Dental floss is easy to use, can be coated with a wax or other substance to ease its insertion between teeth and can be colored, flavored and/or impregnated with beneficial fluoride compounds. While flossing is effective for removal of foreign matter as well as stimulation of gum tissues, it is not, however, thought to be as effective as brushing in removing plaque and staining. Flossing continues to be a well-recommended practice and indeed may still be the only practical way of cleaning the area between teeth which are tightly spaced and will therefore not allow for insertion of other devices.
An alternative or adjunct to flossing, where interproximal spacing permits it, involves use of an interdental brush such as the type available from Butler under the trademark Proxabrush.RTM.. That product takes the form of a small replaceable brush head mounted on a reusable handle. The brush head is formed of a twisted wire spine which defines a central axis from which bristles extend radially outward. In a similar device having a permanent handle, such as that shown in U.S. Pat. No. 4,280,518 to Gambaro, the bristles are of equal length to form a cylindrical array. In another form, the bristle array is tapered in a generally conical shape with the shortest of the bristles being located near the free end of the wire spine to facilitate their insertion between teeth. Handle-mounted interproximal brushes can be used either with or without a dentifrice, are relatively inexpensive and do an effective job of brushing where they can be inserted between teeth from the outer or cheek-facing side of the teeth. However, due to their handles, these devices can be difficult to insert and manipulate properly from the inside (lingual side) of the teeth and can consequently be less effective in cleaning those areas.
Attempts have been made in the prior art to enhance the cleaning capabilities of dental floss by providing it with bristles. U.S. Pat. No. 5,063,948 to Lloyd for example discloses a dental floss having bristled segments defined by a series of radially outwardly projecting bristles. U.S. Pat. Nos. 3,896,824; 4,277,297 and 5,311,890, all to Thornton, disclose string-like tooth cleaning elements having enlarged, spongy portions formed of numerous crimped and crinkled fibers fused to one another at various points. These spongy portions can be drawn through interproximal spaces for cleaning them as well as areas in and around bridges, implants and orthodontic appliances. These devices all retain the advantages of dental floss and, due to their flexibility and lack of a rigid handle, can be inserted and manipulated with relative ease. They too, however, suffer from some significant limitations. To appreciate these limitations, some mechanics of bristle action must be considered.
Bristles clean most effectively when their tips engage the surface being cleaned under a force that lies within a particular range of forces that is related to the stiffness of the bristles. If the force is not great enough, the bristle tips will not engage the surface being cleaned with sufficient pressure to do as effective a job of cleaning as possible. On the other hand, if the force is too great, the bristles will bend so as to engage the surface being cleaned with their sides rather than their tips. This also results in less than optimal cleaning. It is for that reason that toothbrushes are routinely discarded and replaced when their bristles become bent or flattened near their tips.
With the above background, the limitations of the structures disclosed in the Lloyd and Thornton patents can be understood. Because of the flexibility of the structure to which they are affixed, the bristles or spongy fibers of these devices will tend to simply wipe tooth surfaces with their sides rather than forcibly engage them with their tips as they are drawn through interproximal spaces. This will tend to occur because the flexible filament structure from which the bristles protrude will tend to move away from the tooth surface in response to the reaction force generated by contact of the bristle with the tooth. As the interproximal spaces between teeth become larger, such as in patients with receded gums or where gum surgery has been performed, the limitations become increasingly more pronounced. Pulling the floss taut, in an attempt to overcome this effect is not only difficult in light of the space limitations inside the mouth, but would also be risky due to the possibility of cutting the gums with the filament.